1. Field of the Invention
The present invention relates to an integrated technique for a laser diode.
2. Description of the Background Art
In a raster scan exposure unit CTP or DDCP in the prepress and printing industry or a processless output unit (laser imager) for medical application employing a high-power laser diode having a plurality of channels, the number of channels is increased in order to further enhance the output speed.
When the number of channels is increased, however, light source parts are increased in cubic capacity to disadvantageously increase the cubic capacity of an optical system due to the large size of unit light sources forming the plurality of channels. Therefore, improvement is applied for increasing packaging density while enhancing the number of channels.
As a contrivance therefor, a method of separately placing large-sized light source parts and taking out beams emitted therefrom through an optical fiber member for bundling and concentrating the beams in the vicinity of an outlet of the optical fiber member or a method of arranging single-channel light source elements formed by combining can packaging laser diodes and collimator lenses with each other in a spatially crammed state has been employed in general.
In the method employing the optical fiber member, however, the light source parts themselves cannot be miniaturized although the beams can be bundled, and hence the size of the unit is disadvantageously increased as a result. Further, this method is inferior in stability of light output due to severe coupling accuracy between the light source parts and the optical fiber member.
In the method arranging the can packaging light source elements combined with collimator lenses, the size of each single-channel light source forming the minimum unit is relatively increased due to restriction by the size of the can. In order to arrange a large number of light sources, therefore, an optical system having an extremely large aperture is required and hence the size of the unit is so increased that not only the costs for the optical system and the unit are increased but also the optical path is increased to result in insufficient stability due to the optical system of a high reduction ratio.